David J. Margolis, MD PhD is currently an Associate Professor of Dermatology, an Associate Professor of Epidemiology in the Department of Biostatistics and Epidemiology, and a Senior Scholar (core faculty member) in the Center for Clinical Epidemiology and Biostatistics of the University of Pennsylvania. He is an established patient-oriented researcher with an extensive track record of successful research. His research record attests to his commitment to a career in patient-oriented research, which has been focused on the prevention and treatment of chronic wounds, and his desire to be a mentor. He has applied a wide variety of epidemiologic tools and patient-oriented research methods to address research issues. His immediate and long-term career goals center on his desire and intention to continue to evolve and mature as a patient-oriented researcher, teacher, and mentor. Resources available to him,on and around the Penn campus, include all of the components necessary for successful patient-oriented research and mentoring including biostatistical support, data management support, and state of the art research/clinical laboratory services. His patient-oriented NAIMS-funded research project is, after many years of delay, in its first of five years. Most patients with chronic wounds of the lower extremity fail to heal in a reasonable period of time. We have hypothesized that a growth factor associated with wound healing PDGF-BB, when produced in large quantities within the wound bed due to adenovirus mediated gene overexpression by the cells of the wound bed, will dramatically enhance wound healing. This study will use a unique and innovative gene therapy approach, adenovirus-Ad5 and the PDGF-B gene, to insure delivery of a cytokine growth factor to a non-healing wound. The aim of the proposed research study is to assess whether PDGF-BB via in vivo PDGF-BB gene transduction via an intra-ulcer injection of H5.020CMVPDGF-B in patients with a chronic venous leg ulcers can induce the local acquisition of endothelial precursor cells.